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Cam And Head Comparison
The first test uses Dart 215cc heads with the small XR-280 Comp Cams roller cam, the Holley-Dorton single-plane intake, and a 750 Street HP carburetor. Test 2 employs the same as above except with the larger Comp Cams mechanical XR-292 roller cam. The final test is the same combo as Test 2 except we added the Dart CNC 227 heads.

	TEST 1		TEST 2		TEST 3		DIFFERENCE
	Dart 215		Dart 215		Dart 227 CNC
	Comp XR-280		Comp XR-292		Comp XR-292
RPM	TQ	HP	TQ	HP	TQ	HP	TQ	HP
2700	384	197	350	180	353	181	-31	-16
2900	384	212	345	190	347	192	-37	-20
3100	400	236	365	215	361	213	-39	-23
3300	419	263	396	249	383	241	-36 -22
3500	428	285	417	278	410	273	-18	-12
3700	435	307	428	302	429	302	-6	-5
3900	439	326	437	325	443	329	+4	+3
4100	448	350	450	351	457	357	+9	+7
4300	456	373	463	379	467	383	+11	+10
4500	456	391	469	402	475	407	+19	+16
4700	456	408	475	425	484	433	+28	+25
4900	457	426	480	448	489	456	+32	+30
5100	460	447	480	466	491	477	+31	+30
5300	456	460	478	482	490	495	+34	+35
5500	448	470	471	493	484	507	+36	+35
5700	438	476	461	500	477	518	+39	+42
5900	427	479	450	505	470	528	+43	+49
6100	416	483	440	511	462	536	+46	+53
6300	404	485	430	516	452	542	+48	+57
6500	387	479	415	514	443	548	+55	+68
6700	---	428	546	---	---	---	--- ---
Peak	460	485	480	516	491	548
Avg.	431.3	378.9	436.4	387.7	414.7	369.7

Note: The Difference column compares Test 1 with Test 3.

Cam Spec Chart
Cam		Duration	Duration	Lift
	(Adv.)	(@0.050)		Separation	Lobe
Comp XR-280, roller	Intake	280	242	0.609	110
PN 12-771-8	Exhaust	286	248	0.616
Comp XR-292, roller	Intake	292	254	0.622	110
PN 12-773-8	Exhaust	297	260	0.628

Both gross cam valve lifts are calculated using a 1.6:1 rocker ratio. Note that actual (net) valve lift equals gross lift minus lash. Lash was set at 0.016-inch intake and 0.018-inch exhaust for both cams.

Parts List
DESCRIPTION	PN	SOURCE	PRICE
Comp Cams XR-280 roller cam	12-771-8	Summit Racing	$255.95
Comp XR-280 mech. roller cam	12-773-8	Summit Racing	255.95
Dart 215 Pro 1 Platinum heads, pr.	11611123P	Summit Racing	1,439.90
Dart 27 CNC heads, pr.	11971143	Summit Racing	2,551.90
Dart 27 CNC heads, pr.	11971143	Summit Racing	2,551.90

Cylinder Head Flow Testing
Dart 215	Pro 1 Platinum		Dart 227 CNC
Lift	Intake	Exhaust	Intake	Exhaust
		(w/ pipe)		(w/ pipe)
0.100	63	59	65	53
0.200	124	101	145	110
0.300	171	136	197	148
0.400	214	160	242	178
0.500	247	177	272	196
0.600	272	188	283	208
0.700	--	--	287	215

The two-piece Weiand tunnel-ram... read full caption The two-piece Weiand tunnel-ram is assembled using four supplied Allen bolts inside the manifold plenum. We used Loctite to ensure the bolts didn't come loose. We also noticed that the manifold could use some simple port-matching to eliminate the step between the lid and base.	Cam And Head Test	Dart also completely CNC-machines... read full caption Dart also completely CNC-machines the combustion chambers, which is worth some airflow improvements. Those are 2.08/1.60-inch stainless steel valves.
After baselining the Comp... read full caption After baselining the Comp 280 Street Roller cam and Dart 215 package with the 750 Street HP Holley carb, Westech's Steve Brule dove right into changing cams. This was much simpler with the help of a Comp Cams three-piece timing chain cover that eliminated the necessity of dropping the oil pan.	Dart offers the CNC 227 in... read full caption Dart offers the CNC 227 in both bare and assembled configurations. We went with the complete head, which comes with 1.550-inch-diameter dual valvesprings and handled the load of both a 1.6:1 rocker ratio and 6,700 rpm engine speed without complaint.	We flow-tested both the Dart... read full caption We flow-tested both the Dart 215 and the 227 CNC-ported heads so we could evaluate the flow numbers against the power increases.

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